Conventionally known is a jaw crusher in which a substantially vertical stationary jaw is mounted between machine frames, a movable jaw is arranged opposite from the lower portion of the stationary jaw diagonally upwards, the upper end of said movable jaw is supported by an eccentric axis thereby to give a swivel movement to the upper end portion and a vertical swinging movement to the lower end portion, when stones and rocks of larger mass are charged from the upper portion of an opening between said two jaws, and the stones and rocks are crushed under pressure to smaller pieces by means of the motion of said movable jaw, while the crushed stones and rocks are discharged from a discharge port in the lower portion of the opening.
According to the known crusher, the movable jaw is moved under pressure against the stationary jaw by the swivel motion of its upper end portion and the arc motion of its lower end portion whereby the stones or rocks between the jaws are crushed under pressure, the stones or rocks which have become gradually or smaller mass are dropped downwards in order, and the stones or rocks smaller in size than the discharge port in the lower portion are discharged from said port.
With said conventional jaw crusher there is a fear of accident such as being caught by the belt since the eccentric wheel including its fly-wheel is driven through V-belts by motor. Further, there was a great danger of causing injury to humans because it is impossible to quickly stop the operation by vitrue of inertia of the fly-wheel for example, when it is tried to remove foreign articles entered into the crushing chamber.
Furthermore, a motor of great horse power is required to crush stones or rocks of the size greater than a certain extent, and therefore the machine becomes large-sized while increasing its own weight. Moreover, the conventional jaw crusher could not adjust its crushing ability and caused very great noise and vibration.
In addition, the movable jaw driven by an eccentric axis carries out crushing by means of a horizontal movement of an acute triangle on the fulcrum of one end of a supporting rod so that the body to be crushed is crushed in directions whereby it is likely they will become acute-angled bodies.
Thus, there has existed for some time a strong need for a way to remove these various disadvantages and provide a jaw crusher having a high crushing efficiency.